Electronics for high acceleration (high g) and extreme temperature environment applications such as projectile fuzes must survive and function both during and after launching. Modern electronic fuzes have become more complex as demands have increased for electrical as well as mechanical performance options. The increased complexity of fuze systems makes production of fuzes capable of functioning in extreme dynamic and thermal environments even more difficult. Performance reliability and high volume producibility of electronics fuze systems typically decrease as fuze system complexity increases, mainly due to failures at system levels.
A typical electronic assembly in a fuze system comprises various electronic components, including a printed wiring board (PWB), PWB support or housing, connecting wires or pins and sockets, and encapsulant. One of the most critical components of an electronic fuze is the PWB. To produce a high quality PWB which will function reliably requires time-consuming and labor-intensive processes for the steps of laminating fiberglass woven layers, drilling, cutting, adding connectors and standoffs. Most electronic components mounted to a PWB would not be able to withstand the dynamics of gun launching without a mask, PWB housing, and encapsulant material for cushioning, damping, and support of the internal components.
While encapsulant packaging techniques have generally been successful at providing such additional support in a fuze assembly under dynamic environments, such techniques can result in solder cracks and brittle component failures during military standard temperature and humidity tests (per MIL-STD-331). In addition, these encapsulant techniques are not easily controlled, are messy, and typically yield poor reproducibility, e.g., when unpredictable shrinks, cracks, or voids occur within the encapsulant.
Thus, what is needed is an apparatus for electronic fuze packaging with a higher degree of fuze system integration. Such integration is desired to eliminate the use of encapsulant material and reduce the number of components and assembly processes associated with the fuze assembly. By reducing the number of mechanical and electrical interfaces between components in an integrated fuze package, the fuze assembly will achieve a significant improvement in electrical and mechanical performance reliability, improved manufacturability, and reduction of unit cost.